Unlike the radial component of stellar bulk motion, the vertical component, which gets translated as a combination of breathing and bending mode motions, is stronger outside \(R_0\)  than inside. The breathing motion detected in the outer disk confirms the findings of [1]} that there is a notable vertical contraction at \(R>R_0\) . The inner-disk rarefaction-like vertical motion, which was reported by some of the earlier works (e.g. [1]}; [3]}; [4]}), only appears at \(|Z|>2\,\mathrm {kpc}\) . The bending motion derived by outer-disk stars is aligned with the recent findings that an upward bending motion exists at \(R>R_0\)  (e.g. [5]}; [4]}; [7]}; [8]}); by comparison, the downward bending motion inside \(R_0\)  is trivial. The directions for both the breathing and bending motions are mostly invariant with respect to \(Z\) , despite \(Z\) -dependent amplitudes.
